170 research outputs found

    Coal desulfurization by aqueous chlorination

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    A method of desulfurizing coal is described in which chlorine gas is bubbled through an aqueous slurry of coal at low temperature below 130 degrees C., and at ambient pressure. Chlorinolysis converts both inorganic and organic sulfur components of coal into water soluble compounds which enter the aqueous suspending media. The media is separated after chlorinolysis and the coal dechlorinated at a temperature of from 300 C to 500 C to form a non-caking, low-sulfur coal product

    On Connectivity of Wireless Sensor Networks with Directional Antennas.

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    In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models

    Receiver-Side TCP Countermeasure in Cellular Networks.

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    Cellular-based networks keep large buffers at base stations to smooth out the bursty data traffic, which has a negative impact on the user's Quality of Experience (QoE). With the boom of smart vehicles and phones, this has drawn growing attention. For this paper, we first conducted experiments to reveal the large delays, thus long flow completion time (FCT), caused by the large buffer in the cellular networks. Then, a receiver-side transmission control protocol (TCP) countermeasure named Delay-based Flow Control algorithm with Service Differentiation (DFCSD) was proposed to target interactive applications requiring high throughput and low delay in cellular networks by limiting the standing queue size and decreasing the amount of packets that are dropped in the eNodeB in Long Term Evolution (LTE). DFCSD stems from delay-based congestion control algorithms but works at the receiver side to avoid the performance degradation of the delay-based algorithms when competing with loss-based mechanisms. In addition, it is derived based on the TCP fluid model to maximize the network utility. Furthermore, DFCSD also takes service differentiation into consideration based on the size of competing flows to shorten their completion time, thus improving user QoE. Simulation results confirmed that DFCSD is compatible with existing TCP algorithms, significantly reduces the latency of TCP flows, and increases network throughput

    An Enhanced Energy Balanced Data Transmission Protocol for Underwater Acoustic Sensor Networks.

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    This paper presents two new energy balanced routing protocols for Underwater Acoustic Sensor Networks (UASNs); Efficient and Balanced Energy consumption Technique (EBET) and Enhanced EBET (EEBET). The first proposed protocol avoids direct transmission over long distance to save sufficient amount of energy consumed in the routing process. The second protocol overcomes the deficiencies in both Balanced Transmission Mechanism (BTM) and EBET techniques. EBET selects relay node on the basis of optimal distance threshold which leads to network lifetime prolongation. The initial energy of each sensor node is divided into energy levels for balanced energy consumption. Selection of high energy level node within transmission range avoids long distance direct data transmission. The EEBET incorporates depth threshold to minimize the number of hops between source node and sink while eradicating backward data transmissions. The EBET technique balances energy consumption within successive ring sectors, while, EEBET balances energy consumption of the entire network. In EEBET, optimum number of energy levels are also calculated to further enhance the network lifetime. Effectiveness of the proposed schemes is validated through simulations where these are compared with two existing routing protocols in terms of network lifetime, transmission loss, and throughput. The simulations are conducted under different network radii and varied number of nodes

    School closures and educational attainment in Ethiopia: Can extra classes help children to catch up?

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    Data availability statement: The data that support the findings of this study are available in Young Lives at https://beta. ukdataservice.ac.uk/datacatalogue/studies/study?id=7823&type=Data%20catalogue.ORCID: Fiona Carmichael https://orcid.org/0000-0002-7932-2410; Christian K. Darko https://orcid.org/0000-0002-1665-2594; Shireen Kanji https://orcid.org/0000-0003-3512-2596; Nicholas Vasilakos https://orcid.org/0000-0003-3279-2885.Copyright © 2022 The Authors. School closures impact children's attainment adversely, but understanding the effects of closures on children's attainment in lower-income countries is still limited. Addressing this deficit, this study examines how past school closures have impacted children's educational attainment in Ethiopia. The study uses individual student-level data from the Young Lives School Survey and standardised test scores in mathematics and language recorded at the start and end of the school year to model children's attainment. Multiple regression with propensity score matching is used to analyse how attainment over the school year is impacted by school closures for a matched sub-sample of 4842 students. The effectiveness of additional classes to make up for lost learning is also evaluated. Past school closures have had a detrimental effect on attainment in mathematics, but not literacy. Extra classes, specifically those that families do not pay for, have helped children in the past to recuperate lost learning and could serve this function post-Covid-19. Inequalities in learning outcomes, measured by Gini coefficients in educational attainment, are widened by school closures. Applying these results to the extensive school closures under Covid-19 furthers our understanding of the likely effects on academic attainment and can inform policy to mitigate the impact.https://beta. ukdataservice.ac.uk/datacatalogue/studies/study?id=7823&type=Data%20catalogu

    A survey of context-aware recommendation schemes in event-based social networks

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    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. In recent years, Event-based social network (EBSN) applications, such as Meetup and DoubanEvent, have received popularity and rapid growth. They provide convenient online platforms for users to create, publish, and organize social events, which will be held in physical places. Additionally, they not only support typical online social networking facilities (e.g., sharing comments and photos), but also promote face-to-face offline social interactions. To provide better service for users, Context-Aware Recommender Systems (CARS) in EBSNs have recently been singled out as a fascinating area of research. CARS in EBSNs provide the suitable recommendation to target users by incorporating the contextual factors into the recommendation process. This paper provides an overview on the development of CARS in EBSNs. We begin by illustrating the concept of the term context and the paradigms of conventional context-aware recommendation process. Subsequently, we introduce the formal definition of an EBSN, the characteristics of EBSNs, the challenges that are faced by CARS in EBSNs, and the implementation process of CARS in EBSNs. We also investigate which contextual factors are considered and how they are represented in the recommendation process. Next, we focus on the state-of-the-art computational techniques regarding CARS in EBSNs. We also overview the datasets and evaluation metrics for evaluation in this research area, and discuss the applications of context-aware recommendation in EBSNs. Finally, we point out research opportunities for the research community

    Prudence as an ethical foundation for risk management

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    PurposeThis paper aims to draw on historical conceptions of true and false prudence within the broader context of virtue ethics ideas, to create a prudence framework for developing risk-and-ethics cultures in organisations.Design/methodology/approachThe authors use a theoretical analytical approach as a means of examining plausible representations of risk as ethical practice.FindingsWhile the ethical ideal of true prudence is explained primarily with reference to psychological theories of generativity, false prudence is explained as undesirable, primarily with reference to psychological problems of narcissism and the broader dark triad. True and false prudence are represented as centring upon very different motivations for foresight, each of which might set the cultural tone for organisational risk management.Originality/valueThis paper’s main contribution is therefore to call attention to the benefits for organisations of reflecting upon differences between true and false prudence when planning the risk management they want

    Performance Evaluation of Multipath TCP Scheduling Algorithms

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    © 2013 IEEE. One of the goals of 5G is to provide enhanced mobile broadband and enable low latency in some use cases. To achieve this aim, the Internet Engineering Task Force has proposed the Multipath TCP by utilizing the feature of dual connectivity in 5G, where a 5G device can be served by two different base stations. However, the path heterogeneity between the 5G device and the server may cause a packet out-of-order problem. The researchers proposed a number of scheduling algorithms to tackle this issue. This paper introduces the existing algorithms, with the aim to make a thorough comparison between the existing scheduling algorithms and provide the guidelines for designing new scheduling algorithms in 5G, we have conducted an extensive set of emulation studies based on the real Linux experimental platform. The evaluation covers a wide range of network scenarios to investigate the impact of different network metrics, namely, RTT, buffer size, and file size on the performance of existing widely deployed scheduling algorithms

    Activation of the innate immune receptor Dectin-1 upon formation of a 'phagocytic synapse'.

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    Innate immune cells must be able to distinguish between direct binding to microbes and detection of components shed from the surface of microbes located at a distance. Dectin-1 (also known as CLEC7A) is a pattern-recognition receptor expressed by myeloid phagocytes (macrophages, dendritic cells and neutrophils) that detects β-glucans in fungal cell walls and triggers direct cellular antimicrobial activity, including phagocytosis and production of reactive oxygen species (ROS). In contrast to inflammatory responses stimulated upon detection of soluble ligands by other pattern-recognition receptors, such as Toll-like receptors (TLRs), these responses are only useful when a cell comes into direct contact with a microbe and must not be spuriously activated by soluble stimuli. In this study we show that, despite its ability to bind both soluble and particulate β-glucan polymers, Dectin-1 signalling is only activated by particulate β-glucans, which cluster the receptor in synapse-like structures from which regulatory tyrosine phosphatases CD45 and CD148 (also known as PTPRC and PTPRJ, respectively) are excluded (Supplementary Fig. 1). The 'phagocytic synapse' now provides a model mechanism by which innate immune receptors can distinguish direct microbial contact from detection of microbes at a distance, thereby initiating direct cellular antimicrobial responses only when they are required

    A new wildland fire danger index for a Mediterranean region and some validation aspects

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    Wildland fires are the main cause of tree mortality in Mediterranean Europe and a major threat to Spanish forests. This paper focuses on the design and validation of a new wildland fire index especially adapted to a Mediterranean Spanish region. The index considers ignition and spread danger components. Indicators of natural and human ignition agents, historical occurrence, fuel conditions and fire spread make up the hierarchical structure of the index. Multi-criteria methods were used to incorporate experts¿ opinion in the process of weighting the indicators and to carry out the aggregation of components into the final index, which is used to map the probability of daily fire occurrence on a 0.5-km grid. Generalised estimating equation models, which account for possible correlated responses, were used to validate the index, accommodating its values onto a larger scale because historical records of daily fire occurrence, which constitute the dependent variable, are referred to cells on a 10-km grid. Validation results showed good index performance, good fit of the logistic model and acceptable discrimination power. Therefore, the index will improve the ability of fire prevention services in daily allocation of resources.The authors acknowledge the support received from the Ministry of Science and Innovation through the research project Modelling and Optimisation Techniques for a Sustainable Development, Ref. EC02008-05895-C02-01/ECON.Vicente López, FJD.; Crespo Abril, F. (2012). A new wildland fire danger index for a Mediterranean region and some validation aspects. 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